Planer feed mechanism



Feb. 2, 1960 R R, ROBERTS 2,923,210

PLANER FEED MECHANISM Filed Oct. l5, 1954 3 Sheets-Sheetl 1 64 I N VEN TOR.

ROLAND R. Rose-nrs i-f- F/G. BY

Feb. 2, 1960 R. R. ROBERTS PLANER FEED MECHANISM 3 Sheets-Sheet 2 Filed 001,. l5, 1954 INVENTOR. HOLA/VD R ROBERTS Afro/Mfr Feb. 2, 1960 R. R. ROBERTS 2,923,210

PLANER FEED MECHANISM Filed Oct. l5, 1954 3 Sheets-Sheet 3 lll IIO /"`*4 FIG. 8

|50 t5! 22 l l/ |35 ws INVENTOR' ROLAND R. ROBERTS 2O BY at both ends of its stroke.

United States Patenti() PLANER FEED MECHANISM Roland R. Roberts, Irondequot, N.Y., assignor, by mesne assignments, to Farrel-Birmingham Company, Incorporated, Ansonia, Conn., a corporation of Connecticut Application October 15, 1954, Serial No. 462,479

Claims. (Cl. 90-49) The present invention relates to machine tools and more particularly to planers.

In a planer, the work is reciprocated relative to the tool, and the tool is fed relative to the work between cuts, so that on the ensuing cutting stroke more stock will be removed from the work. Usually the work is mounted on a reciprocating carriage which travels back and forth in a horizontal plane under the tool. The tool is usually in cutting position on stroke of the carriage in one direction, and is clapped out of cutting position on the return stroke of the carriage, although in some instances, the tool may be constructed to cut on the strokes of the carriage in both directions. The length of stroke of the carriage is determined by the setting of trip dogs which control the reversal of the carriage at opposite ends of its stroke.

Between cutting strokes of the carriage the tool is fed relative to the work. Tool feed may be depthwise, or lateral. The amount of depthwise feed controls the thickness of chip removed from the work on the ensuing working stroke of the carriage. The lateral feed enables the tool to cut in a different path on the ensuing working stroke, and makes it possible to cover the full surface of the work which is to be planed and to plane the sides of the work.

Large planers are made thirty feet or more in length. In these big machines the carriage has great weight. It is impossible, therefore, to stop the carriage instantaneously. Therefore, it is the practice to have the carriage overtravel The amount of overtravel varies, of course, with the length of the work and the speed of movement of the carriage. Since the amount of `overtravel varies, and since the amount of feed required varies for different types of work, it is necessary to effect for different jobs different numbers of revolutions of the motor which drives the feed mechanism between successive strokes of the carriage, in order to secure the required amount of feed in the time interval allowed by the over- -travel of the carriage. df a considerable amount of feed is -desired between successive strokes of the carriage, obviously the feed drive motor must make more revolutions,

yall things else being equal, than where a relatively slight amount of feed is needed between successive strokes.

' A primary object of the present invention is to provide in a machine tool, and especially in a planer, means for controlling the number of revolutions which the feed drive motor makes during a feed cycle.

Another object of the invention is to provide a feed control mechanism of the character described which is adjustable for'varying amounts of feed.

A further object of the invention is to provide a feed control mechanism of the character described which may V' be usedwith a variable speed motor, and which will be effective, whether the motor be driven at high or low speed,

to'cont'rolthe period that the motor is in operation in a 1feed cycle.

bef used `to control selectively both the lateral and the 'depthwi'seffeed Y a Another object of the invention is to provide a feed control mechanism of the character described which will operate in one direction regardless of the direction of rotation of the drive motor for the feed mechanism.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims.

In the drawings:

Fig. l is an end view of a planer in which the control mechanism of the present invention has been incorporated;

Fig. 2 is a fragmentary, more or less diagrammatic, view showing details of the feed drive of this machine;

Fig. 3 is another fragmentary, more or less diagrammatic view, showing further details of the planer feed mechanism drive;

Fig. 4 is a side elevation, partially broken away, showing on an enlarged scale the control mechanism for the feed;

Fig. 5 is a section taken on the line 5 5 of Fig. 4 looking in the direction of the arrows;

Fig. 6 is a section on the line `6 6 of Fig. 4 looking in the direction of the arrows;

Fig. 7 is a fragmentary end view of the setting dial of the feed control mechanism;

Fig. 8 is an electrical diagram showing how the feed control mechanism may be wired to achieve its purpose; and

Fig. 9 is a fragmentary side elevation of the carriage of the machine showing the trip dogs for tripping the master switch and the master reverse switch, and showing, also, these switches.

The machine, other than for the feed control mechanism, may be of conventional construction. It may comprise a base 20 having uprights or pedestals 21 secured thereto, and a work carriage 22 reciprocable thereon. Mounted on the pedestal 21 above the carriage 22 and bridging the space between the pedestals is a cross rail 24, which may carry one or more saddles 26, on each of which there is reciprocable a tool slide 27. Each tool slide or ram 27 carries a planing tool T. All this is conventional construction and has not been illustrated in detail.

Movement of the carriage may be effected hydraulically, pneumatically, or mechanically. In its movement, as in conventional practice, the carriage is adapted to trip the dogs which control the reversal of the carriage at opposite ends of its stroke. In the case of a hydraulically or pneumatically actuated carriage the trip dogs control the reverse valves that in turn control the direction of ow of the motive fluid to opposite ends of the cylinder in which the piston that actuates the carriage reciprocates. The trip dogs are, of course, adjustable toward and from one another to control the length of stroke of the carriage.

As previously stated, between strokes of the carriage in opposite directions the tool, or tools, are fed relative to the work.

The tool feed is actuated by a motor 30 which is of the variable speed type. The armature shaft 31 (Fig. 2) of this motor drives a shaft 32 through La worm 33 and worm wheel 34. Mounted on the shaft 32 at one side axially of the worm wheel 34 is a spur gear 35. Mounted on the shaft 32 at the other side of the worm wheel 34 is a spur gear 36 (Fig. 3). The spur gear 35 meshes with and drives two pinions 37 and 38. These pinions are rotatably mounted on shafts 50 and 51, respectively. They are adapted to be selectively coupled to these shafts to drive the same by means of the clutches 52 and 53, respectively.

Shaft 51 is a screw shaft which threads into a nut 54 (Fig. l) in the saddle 26, thereby to effect horizontal feed of the tool T. Shaft 50 drives through gearing (not shown) a vertical screw shaft (not shown) which engages a nut on the slide 27 that carries the tool T.

This slide is movable vertically to control depthwirse feed o'ft'he'to'ol into the work.

One or other of the clutches 52 and 53, which couple the pinions 3.7 and 38, respectively, to the shafts, S and 51, respectively, is yengaged manually at the start of operation lofv the machine depending upon whether the tool is to be fed depthwise or laterally between strokes of the work carriage. The drive from the motor 3,0 tothe saddle 26 and to the slide 27 is conyentional.

The gear 36 (Fig. 3) meshes with and drives a gear 60,. which is fastened to one end of a shaft 62.V This shaft isjournaled in the control box 64 (Figs. 4, 5 and 6).` It has a bevel gear 65 keyed toit which meshes with two coaxial, oppositely disposed, bevel miter gears 66 and 67, thereby driving.' these two gears in opposite directions. These two gears are connected by convenwork carriage between working tional one-way clutches 68 and 69 (Fig. 5), respectivev ly, with a shaft 70. The shaft 70 is disposed at right Vangles to shaft 62, and is journaled adjacent opposite ends in suitable bearingl members 71 and 72, whichV` are secured by screws 73 and 74, respectively, in the housing 64.

Secured to the inner end of the shaft 70 by a set'screw 75 is one member of a conventional magneticclutch .which is denoted as a whole at 80. Another member of this clutch is secured to the inner end of a shaft 81, which is axially aligned with the shaft 70.

Y YShaft, 81 is journaled on bushings 83 in a bracket'v 8 4 which is fastened by bolts 85 in the housing 64. Shaft 81 has an enlarged head 90` intermediate its ends to which thereis secured by screws 91 a disc or plate 92.

This discis connectedby a pin 93 tothe outer end ,of

a spiral coil spring 95. The inner end of this springis connected by a pin 96fto thebracket 84. Y

' -Rotatably mounted upon. theshaft 81 is a sleeve 100 with which Vthere is integral another disc 102. Disc y102 is coaxial with disc 92 Iand is formed on its outer face adjacent its periphery Iwith an arcuatek cam lobe 103 (Figs. 4, 5 and 6), that extends partway around its axis. This cam lobe has rise portions 101 and 104 at opposite. ends.

The disc 102 is adjustable angularly relative to the disc 92 andY is adapted to be coupled vto the disc 92 in any adjusted position by a conventional toothed coupling 105 (Fig. 5), comprising'an external toothed member on the disc 102 and an internal toothed member onvthe disc 92. This coupling is normally held in engagement by a coil spring 106 which is yinterposed between the head of a screw 107 and an internal shoulder108'formed in the sleeve 100. The screw 107 threads into the shaft 81.

The disc 102 is adapted to be adjusted angularly so that the cam lobe 103 will actuate selectively one or both of the two conventional limit switches 110 and 111 (Figs. 6 and 4) which are secured by screws 112 and 113,respectively, in the housing 64. By rotating the cam disc 102, when it is uncoupled from disc 92, `cam lobe 103 will be actuated to trip one or both of the limit switches 110 and 111. The raisedy portion of the cam lobe', vwhen rotated, will depress the plunger of one or both of these limit switches dependingon the angular position to which the cam lobe is rotated. The limit switches are connected withthe vfeed motor in c011- ventional manner to control therate vof speedk at which this motor runs. The switch 110, for instancermay-be used to shift the motor to its low speed rate to; decrease the 'r.p.m. of thef motor 30, while the switch '.1111 maybe used to shift the 4motor to itsfhigh speed rate' toincrease thel r.p.m.

It is desirable to have the motor run at low speed in order to decrease the over-run of the motor due to farmature inertia. This decreases .thepereentage oferror in the number of revolutions of the motor in low feed.

achieved in the time interval allowed by overrunV of ,the

.Where a relatively large amount of feed hasI ,tof be strokes, the motor must be run at high speed in order to attain the number of revolutions of the motor required to achieve the desired amount of feed. For this purpose cam lobe 103 is adjusted angularly, upon uncoupling of cam disc 102 from disc 92, to bring it into engagement first with the plunger of limit switch 111 to trip that limit switch.

The amount ofA feed is adjusted by use of; a graduated disc 115 (Figs. 4, 5 and 7) which is fastened by screws 116 to the sleeve 100. Dis'c 115 may be graduatedlin fractions of an inch as shown inV Fig. 7. Thegraduations of disc 11S readfagainst azero mark on thecover 117 of the control box` housing., Cover 117 is secured to the housing by screws 119. By pulling the sleeve outwardly with reference to the shaft 81 against the resistance of the spring 106, the coupling can be disengaged. Then the sleeve 100 can be rotated to rotate the disc 1,02 relative tothe disc 92, thereby to. position the cam lobe 103 tofoperate Veither, the .limit switch 110 or bothY thelirnit switch 111and Ythe switch 110 successively.

The. cam Ydisc 102fhas a lugJ 120` (Figs. 5. and 6) integral with it. This lugisY adapted to engage a plunger 12,2 of a limit switch 123 that is mounted in housingf64. kLimitA switch 123 is operativelyf connected to magnetic clutch 80 and motorf30 to deenergize the clutch 80 and stopthe motor 30, when the switch is tripped by lug 12,0. i L ugv120, therefore, determines the time that the, feed rnotor 3,0.,fruns, that is, the number of revolutions which ther feed motormakes in a cycle. In the position shown in .Figk 6, Vthe controllerA isset for. the maximumfeed; the cainvlobe103 has. been positioned,r by uncoupling coupling 92 and rotating disc'102,so.as.to trip. switch 1'11 first; andthe lug 12.0 has" been" positioned atthe furthestf possible point angularlyawayfrorn plunger 122'. The directionof travel of the disc.102, whencoupled to disc;92,is. indicated. by thearrow. 118in Fig, 6. In Fig, l5disc 102 isshown adjustedt-oy azdiierent position whereV lug v is much closer towplunger 12,2 and` will trip switch 110 but not switch111. The disc 1 02 can be adjusted to any angle about the axis of the shaft 81 from zero` to the position shown in Fig.Y 6 where'lug 120 is k324 away from zero. f

A master reverse switch (Fig. .8)Yoperated; by a trip dog on the carriage of themachine energizes the magnetic clutch 80 (Fig.Y 5) at theend ofA each return stroke of the carriage. At the same time, amasterswitch 136 (Fig. 8), also operated by a trip dog 151Y (Figf) on the carriage, starts the motor 30. If desiredfthe sam switch mightbe used for both these purposes.

As soon as the motor 30 starts to run, screw shaft ,51 is rotated to effect lateral feed of saddle .26 and tool T, vif clutch 53 has been engaged, or to effect depthwisefeed of slide 27 andl tool T, if clutch 52` has'been engaged. Simultaneously motor 30 drivesy cam disc. 102. This drive is from the motor 30 through the gearingg33, 34, 36, 60, 65,7and 66 or 67, dependingpupon the'direction of rotation of motor 30, shaft 70, coupling-80shaft 81, disc 92, and coupling 105. If the disc 102 has been adjusted to a position, such as shown in Fig. 7 6, where thelirnit switch 11,1 has been tripped, the variablespeed motor 30 will operate at high speed as long asthecam lobe 103 isinengagement with the limit,switchf,111;.then

651 the limit switch 110 will be tripped by thecam lobe -to slow the motor down again.` If thefdisc-llhasgbeen adjusted initially angularly relative tothedisc 92;sojthat it will only actuate the limit switch y110, themotor 30 will revolve at low speedruntil stopped.. Of course.. the initialY angular adjustedposition of ,the .disc ,102deter' mines when thelug 1,20 comes into operation. Thiswill determine the number of revolutions which themQton- SD makes before it is stopped; and this determines the amount of feed of the Vtool in the feed cycle. p

The koperation of the motor30 and of thefeedshaft 50 or 51 continues until .the lug 120 strikesthegapluner izz fthe iimitswitch 12s. This trips'this limit switch and deenergzes the magnetic clutch 80, stopping the cam disc 102 and motor 30. This occurs before the carriage 22 on its reverse stroke has brought the work to a position to be engaged by the tool. In other words, the carriage overtravels a sutlicient distance to permit the tool t be fed depthwise toward the Work or laterally relative to the work by the amount of the chipwhich itis desired to remove from the work during each working stroke, before the tool actually engages the work on the working stroke.

Since the disc 102 is adjustable angularly to different positions, the amount of travel of the disc before the lug 120 strikes the plunger 122 of the limit switch 123 is variable.

When the magnetic clutch 80 is deenergized the spiral spring 95, which is wound during rotation of the shaft 81 in the housing, returns the discs 92 and 102 to their :starting positions. There is a lug 125 on disc 92. Engagement of this lug with a bumper, which is mounted in a bolck 126 (Fig. 6), that is secured by screws 127 to the housing 64, cushions thereturn movement of the disc. This bumper includes the coil spring 128.

A pin 130 on the disc 102, which is positioned to engage with a pin 131 on the disc 92, determines the maximum angular starting position to which the disc 102 may be set away from zero.

Fig. 8 shows one way in which the control mechanism may be wired to accomplish its purpose. L1 and L2 are the main lines. When switches 135 and 136 are closed by tripy dogs on the carriage 22, circuits are closed to the magnetic clutch S0 and to the variable speed motor 30. The circuit to the clutch 80 is from the main line L; through the normally closed switch 123 the lines 137 and 138, the now-closed switch 135, the line 139, the clutch 80, and the line 140 back to the main line L2.' The -circuit to the motor depends initially upon the initial position of adjustment of the member 102. If the control member 102 is adjusted so that it closes the switch 110, the circuit is from the main line L1 through the switch 123, the lines 137 and 142, the now-closed switch 110, the line 143, the controller 141 which controls the low speed winding of the motor, the line 144, the now-closed switch 136 to the main line L2. If the control member 102 has been adjusted initially far enough away from stopping position to close the switch 111, then the circuit to themotor is through that switch, the line 146, the controller v145 which controls the highspeed winding of the motor, the lines l147 and 144, the now-closed switch v,136 to the main line L2. When the high portion of the .cam lobe 103 Ypasses beyond the Vplunger of the limit `switch 111, the switch 11,1 will be opened; and the high speed operation of the motor 30 will stop, but the switch 110 will be closed to cause the motor 30 t0 operate at low speed until it is stopped by opening the switch 123.

As will be obvious from the preceding description, in the device of the present invention, the feed mechanism is operated by a variable speed motor. The length of time that the motor runs, that is the number of revolutions which it makes, in a feed cycle is controlled by the position to which lug 120 is adjusted in adjustment of cam disc 102. The speed of the motor is controlled also by the position to which the disc 102 is adjusted, through the microswitches 110 and 111 and the cam 103. How- .ever, the disc 102 can be adjusted through an angle of ,approximately 180 before shifting from high to low ,speed operation of the motor and vice versa. The direcftion of rotation of the motor is changed for lateral feed iin the required direction when cutting opposite sides, respectively, of a workpiece. However, the cam disc `102 ;is driven in the same direction regardless of the direction .of rotation of the motor.

While the invention has been described in connection with a machine in which the work carriage is reciprocable with reference to the tool, it will be understood that it is usable also in a machine where the work is stationary and the tool travels relative to the work in the cutting stroke. Moreover, the invention is not limited to planers, but may be used on slotters, surface grinders and other types of machine tools.

While the invention has been described,` therefore, in connection with a specific embodiment thereof, it will be understood that it is capable of further modification; and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within l known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. In a feed mechanism the combination with a variable speed motor, of means for controlling the number of revolutions of said motor in a feed cycle, comprising a housing, a shaft journaled in said housing, a rotary control member journaled in said housing and having a cam portion of less angular extent than the angular extent of said control member, means for coupling said control member to said shaft to drive said control member from said shaft, means for driving said shaft from said motor, a trip member carried by said control member and operative on rotation of said control member Ifor disconnecting the first-named coupling means and for stopping said motor, a pair of switches operative, respectively, when closed, to effect, respectively, different speeds of operation of said motor, said switches being positioned in angularly spaced relation about the axis of said control member to be actuated by its cam portion when engaged thereby, said control member being adjustable manually about its axis of rotation when uncoupled from said shaft to position said trip member and said cam portion at a predetermined position relative to motorstopping position, and a spiral coil spring secured at one end to said housing and connected at its other end to said control member for returning said' control member to its initial adjusted lposition upon disconnection of said last-named coupling means.

2. In a feed mechanism, the combination with a variable speed motor operable at both high speed and low speed, of means for controlling the number of revolutions of said motor in a feed cycle, comprising a first shaft, a rotary control member, means for coupling said control member to said first shaft so that said control member rotates on rotation of said shaft, a second shaft, means for driving said second shaft in a. constant direction regardless of the direction of rotation of said motor, electro-magnetically-operated means for coupling said first shaft to said second shaft to drive said first shaft from said second shaft, an electrical limit switch operatively connected to the last-named coupling means and to said motor, and trip means actuated on rotation of said control member to a predetermined position to trip said switch to deenergize said last-named coupling means and disconnect said first shaft from said second shaft and stop said motor, a pair of switches operative, respectively, to effect, respectively, high speed and low speed operation of said motor, said control member having a face cam portion on one end face and being movable axially to uncouple it from said shaft, said switches being positioned in angularly spaced relation about the axis of said control member to be closed when engaged by said cam portion, said control member being adjustable manually about its axis of rotation when uncoupled from said shaft to position said trip means at a predetermined distance from motor-stopping position and to position said face cam portion for actuation selectively of one or both of the two switches.

3'. Inv a feed mechanism, thecombination with a variable speed' motor, of' means for controlling the nurnber of revolutions of said motor ina feed cy'cle, comprising a housing, a" shaft journal'ed in s'aid housing, a rotary disc coaxial with said shaft, electromagneticallyoperated means-for coupling said disc to said aftl to drive said discifrom said shaft, a spiral coil's' in'gfcon'-l nected aty one end' to said housing and at its" opposite end to saidv disc to be wound on rotationof' sa'idf disc, a earn disc journaled in said housing in a'Xial' alignment with the rst-named disc, means for coupling said cam dis'c to saidfirst-named" disc to rotate saidl cam" disc on rotation of said 'rstinamed' disc, meansy comprising a' bevel gear', two opposedI miter gearsY rneshingl withi said bevel gear, and a' pairj of one-Way clutches` for vdrivi'rg said shaft in one directionl from said motor regardless of theV direction of rotation of said motor, a switchV o"p` eratively connected to said electroniagneticallylop'erated coupling means and to' said motor to deene'r'giz'e said electroma'gnetically operated coupling means'an'drto stop said motor upon being tripped, trip means carried by said cam disc for tripping said switch upon rotation -of said cam disc througha predetermined angle',a`1p`a'irof switches operative, when closed,' to eifect,2respectively,' different speeds of operation of! said motor,l said' cam di'sc having a cam portion extending part-way only' around one'of its side faces, the two switches of! said pair of switches being positioned to be closed upon' engagement therewith of said camportion, the last-named coupling means being disconnectable by 'axial movement offsaid cam disc to permit' manual rotative adjustmentof said camdisc relative to said first-named disc toposition said trip means' at a predeterminedV distance from'- tripping position, and 'to bring' said cam portion intoposition to engage one or both of theswitch'esiof said pair of switches uponV the.r rotation ofsaidca'in disc.r

4f.y Inv a machiner tool' havingv a -Work support, a'f tool support, and a tool carried by said toolsuppo'rt, one of saidk supports being reciprocablefrelative to the other through a distance sufcient to effect machining ofthe work by thetool and'overtravel of the work relative to the tool, means for effecting feed of the tool periodically relative to the work during theovertravel'comprisinga variable speed motor, a rotary control member, said con trol member havinga cam portionthereonwhose angular extent'is less than the angularv extent o'fsaid control member, meansfor couplingsaid control member to said motor to drive saidilcontrolm'ember from said motor during operation of. said motor, switches'spaced angularly'about said control member, and adapted to effect, respectively, relatively 'high speed and relatively low speed 8 operationof s'idf motor, saidA control rnembei being dil` posedi'to trip said switches upon engagement of its""c`a'm' prtil' therewith, said'control member-being adjustable abouty its axis of rotation, when uncoupled' :fro'rnsaid' ni'crtcfrgdoiinitiallyr position the cam porfiend'of saidI contrer riber relative 't'o said switches, meansconst'antly biasl` ing'salid Yeortf'rol member to return to' its adjusted posi; tion' nie'ans actuated by the reciprocable support during ov sling-'means aridfmeans actuated by' said central mede ber for stopping said motor afterV a predetermined' feed and coupling" saidj coupling means to permit said control rnrribr to be reset toits initial adjusted position; v'

- 5'.Y In av feed mechanism,` the combination with variable speed motor, of means for controlling thehui ber ofV revolutions' of saidV motor in' a feedcycle'comf prisingashaft, a rotary control memberha'ving al' c'ai` portion thereon of less angular extent thansaid control memberl itselffrneans for coupling saidv control member to saidsliaft to drive said control memberfon rotation of said4 shaft, means for driving said Yshaft from said r'oto', and means carried by saidA control member and operable' at VaVY predetermined point in its' rotation" tb uncouple said control memberfrom said shaft and to stop" said motor, said control member being rotatably-tatlL justablerelativeto said shaft to initially positiony thelasti named means at a selected angular" distance away-fiom s'aidpr'edeterminedpoint, and av` pair? of limit switches disposed! at different'y angular positions aboutv theaxis'of said"-control mer'nbery so` that one or both of saidisw'itch'efs is or are operatedy by saidcam portionL when engaged thereby'in the rotationof rsaid controlmember-depend? ig vruponi the initialadjustedposition of saidcontrl-mein bei', said limit switches being operativelyconnected 'to 4saidy motor toetfect, respectively, relatively high aiid relativelylowepeed operation of said motor, arid means fr-f'retu'rni'ng saidl controlmember to initial adjusted position whenit is vuncoupled'from said shaft.-

, References Cited in the le of this-patent l UNITED STATES PATENTSl 771,373 Langenl oct; 4, 1904 894,232 Richards Ju1'y'f28, 1908 1,008,593 Fish Nov; 14,1911 1,560,6534 Bladder a1. Nds/10,1925 1,678,302.A Raddmph -Ju1y '24; 19128 2,405,686V C1ark Aug.' 13',l 1946 2,469,594 Danforth Mj/"10, 1949 2,521,801'V Mozzanini et kd1. sept.12j, 1959 2,575,792 Ballard er a1. Nov';'20,195'i 2,594,782 Makadi et al'. Apr; 29, 1952 el" for starting saidmotor and coupling said c'ouf. 

